<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<style>
	   .input-val {
		width: 200px;
		height: 32px;
		border: 1px solid #ddd;
		box-sizing: border-box;
	  }
	  #canvas {
		vertical-align: middle;
		box-sizing: border-box;
		border: 1px solid #ddd;
		cursor: pointer;
	  }
	  .btn {
		display: block;
		margin-top: 20px;
		height: 32px;
		width: 100px;
		font-size: 16px;
		color: #fff;
		background-color: #457adb;
		border: none;
		border-radius: 50px;
	  }
	    </style>
	<body>
		<div class="code">
			<input type="text" value="" placeholder="请输入验证码（不区分大小写）" class="input-val">
			<canvas id="canvas" width="100" height="30"></canvas>
			<button class="btn">提交</button>
		</div>
	</body>
		<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-2.1.1.min.js"></script>
	<script>
	    $(function(){
	        var show_num = [];
	        draw(show_num);
	
	        $("#canvas").on('click',function(){
	            draw(show_num);
	        })
	        $(".btn").on('click',function(){
	            var val = $(".input-val").val().toLowerCase();
	            var num = show_num.join("");
	            if(val==''){
	                alert('请输入验证码！');
	            }else if(val == num){
	                alert('提交成功！');
	                $(".input-val").val('');
	                // draw(show_num);
	
	            }else{
	                alert('验证码错误！请重新输入！');
	                $(".input-val").val('');
	                // draw(show_num);
	            }
	        })
	    })
	
	    //生成并渲染出验证码图形
	    function draw(show_num) {
	        var canvas_width=$('#canvas').width();
	        var canvas_height=$('#canvas').height();
	        var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
	        var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
	        canvas.width = canvas_width;
	        canvas.height = canvas_height;
	        var sCode = "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
	        var aCode = sCode.split(",");
	        var aLength = aCode.length;//获取到数组的长度
	        
	        for (var i = 0; i < 4; i++) {  //这里的for循环可以控制验证码位数（如果想显示6位数，4改成6即可）
	            var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
	            // var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
	            var deg = Math.random() - 0.5; //产生一个随机弧度
	            var txt = aCode[j];//得到随机的一个内容
	            show_num[i] = txt.toLowerCase();
	            var x = 10 + i * 20;//文字在canvas上的x坐标
	            var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
	            context.font = "bold 23px 微软雅黑";
	
	            context.translate(x, y);
	            context.rotate(deg);
	
	            context.fillStyle = randomColor();
	            context.fillText(txt, 0, 0);
	
	            context.rotate(-deg);
	            context.translate(-x, -y);
	        }
	        for (var i = 0; i <= 5; i++) { //验证码上显示线条
	            context.strokeStyle = randomColor();
	            context.beginPath();
	            context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
	            context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
	            context.stroke();
	        }
	        for (var i = 0; i <= 30; i++) { //验证码上显示小点
	            context.strokeStyle = randomColor();
	            context.beginPath();
	            var x = Math.random() * canvas_width;
	            var y = Math.random() * canvas_height;
	            context.moveTo(x, y);
	            context.lineTo(x + 1, y + 1);
	            context.stroke();
	        }
	    }
	
	    //得到随机的颜色值
	    function randomColor() {
	        var r = Math.floor(Math.random() * 256);
	        var g = Math.floor(Math.random() * 256);
	        var b = Math.floor(Math.random() * 256);
	        return "rgb(" + r + "," + g + "," + b + ")";
	    }
	
	</script>
</html>
